As a method of producing an amide compound from an acylfluoride group-containing compound, the direct reaction of the acylfluoride group-containing compound with an amino compound has so far been adopted. These compounds are known to react stoichiometrically with each other.
In this reaction, hydrogen fluoride is produced as a by-product. If the amino compound is used in excess of its stoichiometric amount, the hydrogen fluoride produced combines with the excess amino compound to form an amine salt.
On other hand, there is known a case in which an amino compound as acid acceptor is further added to the reaction system. In such a case, an amine salt is also formed between the hydrogen fluoride and the amino compound added.
In order to isolate an intended amide compound by removing the salt(s) formed by hydrogen fluoride and amino compound(s) (hereinafter called amine hydrofluoride(s)) from the reaction system, it is prevalent to adopt an after-treatment with water.
However, it has sometimes occurred that amide compounds produced had poor separability from water. Under such a situation, the conventional direct reaction method has problems such that it requires considerable hours and many separation steps to obtain an intended amide compound in a highly pure form, a large quantity of amine hydrofluorides remain in the products obtained because of incomplete purification, reduction in yield is unavoidable, and so on.
In another case, it is possible to isolate the intended amide compounds by distillation. Even if it is so, in so far as the removal of amine hydrofluorides is incomplete in the step prior to distillation, the distillation step suffers troubles such that amine hydrofluorides contaminate distilled fractions through their sublimation during the distilling operation and occasionally deposit in the cooling zone of a distilling column to clog the distilling column.